1. Field of the Invention
The present invention relates generally to security surveillance devices and more particularly to surveillance cameras.
2. The Prior Art
In photography, lens angle and aperture setting determine size of the field and amount of light of the exposure, respectively. The efficacy of identifications of a subject or activity under differing conditions depends on the suitability of the particular lens settings to the conditions present in the area being surveyed at the moment such subjects or activities are photographed.
In the field of hidden camera surveillance, in which either a still camera takes photographs periodically or a movie camera or video camera is operating, known devices require that both the lens angle setting and the aperture setting be determined in advance. Whereas, such devices have proven valuable, because of the necessity of presetting, they sometimes give less than satisfactory or, even, unusable images.
Often, outdoor light conditions change because of the position of the sun, the advent of dawn or dusk, or a change in cloud conditions. Light conditions can also vary such as when an entranceway looking in or out is being viewed and the subject moves from indoors to outdoors or vice-versa. Also, if the room is lighted mainly by natural light, the same factors mentioned for outdoor variations can effect the indoor light conditions. Successful nightime surveillance can be hampered if the subject includes its own light source such as a flashlight or headlamps on a vehicle. Although, in general, traditional surveillance cameras have been helpful in subject identification, they have not been entirely satisfactory in situations wherein an adjustment of the aperture setting is required to compensate for variable light conditions.
Similarly, subjects within a viewing field do not always remain static. In some instances it might be desirable to view a large group of people and a, therefore, large field of vision is needed. However, at the next moment, a narrow field might be desirable for individual identification. Key activity might occur at different locations calling for a wide viewing field in yet other situations. Further, it might be desirable to watch both an entire storage area, plus have close-ups of a particular portion thereof, such as where a safe or high value property is located. Traditional surveillance cameras having a static field, while being helpful generally, are less than satisfactory in these and other situations.